tech-debt(forks): resolve the 'api' batch of symbol-fork baseline clusters — merge real forks, rename homonyms apart #18451

Parent: #17312. Triage method: #12771 (same name is not the same concept).

A batch of repo_tests/symbol_fork_baseline.json clusters whose files (22) touch no file of any open PR as of 2026-10-12, so it can be worked in parallel with the other batches.

Clusters: get_engine, SecurityVulnerability, SecurityAnalyzer, get_redis_connection, APIRegistry, QueryIntent, SessionSummary, MCPTool, TemplateSearchResponse, TemplateCategory, WorkflowTemplate, WorkflowControlRequest, list_terminal_sessions

Acceptance criteria

• Each cluster is classified with evidence, as either a REAL FORK (same concept) or a HOMONYM (different concepts, same name).
• Real forks are merged into ONE canonical definition, and every caller is repointed (grep the behaviour, not just the symbol).
• Homonyms are renamed apart, with names that say what each one is.
• Every resolved name is removed from symbol_fork_baseline.json; the ratchet only shrinks.
• Each merged fork has a test showing the canonical definition serves the former callers.